Physical and Chemical Compatibility Testing of Intravenous Phenytoin Preparations In 0.9% Normal Saline Solution

Abstract

Intravenous (IV) phenytoin sodium preparations have high pH values (>12) and present compatibility problems with admixtures. Hence, it is necessary to dissolve it in normal (0.9% w/v) saline to adjust the pH to avoid incompatibilities with other medicines, stability, and prevent phlebitis. This study aims to determine the physical and chemical incompatibility of IV phenytoin preparations in normal saline over a certain period. Physical testing of IV phenytoin in normal saline, including organoleptic particle size and pH measurements at 0, 3, and 6 hours. Chemical stability testing was carried out by measuring the concentration of the preparation for 8 hours using a UV spectrophotometer, testing the functional groups of phenytoin IV precipitates in normal saline using FTIR and molecular weight using GC-MS. The results of testing the concentration of phenytoin samples A, B, and C showed instability in the preparations. In the FTIR test, the sample showed absorption bands at 1752 cm-1 for the amide (C=O) functional group, 744 cm-1 for the phenyl C-H group, and 1286 cm-1 for the C-N group. Results of the physical characteristics test showed no increase in pH of more than 1 unit from 0, 3, and 6 hours for the three samples tested, but there was an increase in turbidity of the preparation from visual observation. The MS analysis showed that the pure phenytoin and the precipitated preparation have the same molecular weight of 252.1 m/z.